Magnetic cylinder for printing presses

ABSTRACT

A magnetic printing cylinder in which a magnetic assembly that slides onto a cylinder hub between bearers is clamped between threaded rings and held against rotation by a key. The assembly consists of alternate thin non-magnetic carrier ring means and thin annular magnetic pole pieces which have continuously abutting planar faces and are secured between annular nonmagnetic plates by several tie rods. Each carrier ring means has several circumferentially spaced magnet mounting holes, and magnets in the holes of alternate carrier ring means have their poles reversed so like poles abut both faces of each pole piece and alternate pole pieces are of opposite polarity. Radially projecting register pins are embedded in the assembly.

United States Patent [191 Kostal Nov. 18, 1975 1 1 MAGNETIC CYLINDER FOR PRINTING PRESSES [75] Inventor: Louis Kostal, Downers Grove, Ill.

211 App]. No.: 451,364

[52] US. Cl. 101/378; 101/382 MV; 29/125 [51] Int. Cl. B41F 13/10 [58] Field of Search 100/299 M; 101/378, 382 MV,

[56] References Cited UNITED STATES PATENTS 2,952,205 9/1960 Dunwoodie 101/382 MV 3,097,598 7/1963 Hotop et a1. 101/382 MV 3,438,324 4/1969 Meade et a1. 101/378 3,496,866 2/1970 Nystrand 101/378 3,721,189 3/1973 Bray 101/382 MV 3,742,852 7/1973 Leffler et al. 101/378 3,824,926 7/1974 Fukuyama 101/382 MV Primary Examiner-Edgar S. Burr Assistant ExaminerR. T. Rader Attorney, Agent, or Firm-Wegner, Stellman, McCord, Wiles & Wood [57] ABSTRACT A magnetic printing cylinder in which a magnetic assembly that slides onto a cylinder hub between bearers is clamped between threaded rings and held against rotation by a key. The assembly consists of alternate thin non-magnetic carrier ring means and thin annular magnetic pole pieces which have continuously abutting planar faces and are secured between annular non-magnetic plates by several tie rods. Each carrier ring means has several circumferentially spaced magnet mounting holes, and magnets in the holes of alternate carrier ring means have their poles reversed so like poles abut both faces of each pole piece and alternate pole pieces are of opposite polarity. Radially projecting register pins are embedded in the assembly.

17 Claims, 4 Drawing Figures USO Pamnt Nov. 18,1975 Sheet 1 of2 9 9,919,937

US. Patent Nov. 18,

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Sheet 2 of 2 J f0 20a AMA/5 MAGNETIC CYLINDER FOR PRINTING PRESSES BACKGROUND OF THE INVENTION A well recognized type of plate cylinder for rotary printing presses uses permanent magnets in the cylinder in conjunction with magnetizable pole pieces to retaln printing plates on the cylinder. Reference is made, in this regard, to Dunwoodie U.S. Pat. No. 2,952,205 and Hotop et al. US. Pat. No. 3,097,598, for prior art which is believed to be the most pertinent to the present invention.

The prior art devices are relatively expensive to build, and at least in the case of the Dunwoodie device are incapable of producing sufficient magnetic force for use in high speed presses.

SUMMARY OF THE INVENTION In accordance with the present invention, a magnetic assembly is made in the form of an open ended cylinder which may be slid endwise onto a hub of a shaft and locked in placed by threaded clamping rings and a key and keyway arrangement, after which the bearers are mounted on the ends of the shaft by a shrink fit.

The magnetic assembly consists of alternate thin nonmagnetic carrier ring means and thin annular magnetic pole pieces which have continuously abutting planar faces and are secured between annular non-magnetic end plates by six tie rods. Each carrier ring means has several circumferentially spaced magnet mounting holes, and magnets in the holes of alternate carrier ring means have their poles reversed so like poles abut both faces of each pole piece and alternate pole pieces are of opposite polarity.

The assembly is provided with radially projecting register pins which are engaged by register holes in printing plates so as to assure plate registration and prevent circumferential creep of the plates. The register pins are screwed into bushings that are press fitted into the magnetic assembly.

THE DRAWINGS FIG. 1 is a fragmentary side elevational view of a magnetic printing cylinder embodying the invention, with parts in section;

FIG. 2 is a fragmentary longitudinal sectional view on an enlarged scale, taken substantially as indicated along the line 22 of FIG. 1;

FIG. 3 is a sectional view on an enlarged scale taken substantially as indicated along the line 3-3 of FIG. 1; and

FIG. 4 is a fragmentary sectional view on an enlarged scale showing the mounting of a register pin.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings in detail, a magnetic printing cylinder consists of a shaft, indicated generally at a magnetic assembly, indicated generally at 11; clamping collars 12; and bearers 13.

As best seen in FIG. 2, the shaft 10 includes a hub 14 of uniform diameter the two ends of which are threaded as at 15. Immediately adjacent the threaded areas 15 are areas 16 of reduced diameter, and at the ends of the shaft are spindles 17 of still further reduced diameter. The hub 14 of the shaft is provided with a longitudinal keyway 18. A key 19 is press fitted into the keyway 18.

The magnetic assembly 11 is best seen in FIG. 2 to consist of thin, alternate carrier ring means 20 of nonmagnetic material such as stainless steel or brass, and thin annular pole pieces 21 of magnetic material such as mild steel; and the carrier rings and pole pieces are mounted between non-magnetic end plates 22 by means of a plurality of tie bars 23 which impale the end plates, the carrier ring means and the pole pieces.

The carrier ring means 20 and end plates 22 make a sliding fit on the hub 14, while the pole pieces 21 have central holes 210 one-half inch larger than the hub to leave a gap between the hub and the pole pieces. This prevents dissipation of the magnetic force of the pole pieces through the shaft, which is necessarily of a type of steel that has substantial magnetic properties.

As shown in FIG. 2, each of the carrier ring means 20 consists of two identical, thin stainless steel plates 20a and 20b. Each of the plates 20a and 20b is 0.060 inch thick, and the reason for using two plates of that thickness rather than a single plate of twice that thickness is that the thinner gauge of stainless steel is easier to fabricate.

The plates 20a and 20b which form the carrier ring 20 are provided with circumferentially spaced holes 24 to receive thin ceramic magnets 25. The carrier ring means 20 and the magnets 25 provide planar faces that are in effectively continuous abutment with planar faces of the pole pieces 21, so the entire assembly requires a minimum amount of machining and fitting of parts.

The ceramic magnets 25 are magnetized across their narrow dimension, and alternate magnets have their like poles adjacent each other so that each pole piece 21 except for those adjacent the end plates 22 has like magnetic poles abutting both of its faces, and the pole pieces are necessarily alternately of opposite polarity.

As seen in FIG. 3, the plates 20a and 20b and the end plates 22 are provided with aligned notches 26 which cooperate to form a keyway which engages the key 19 in the keyway 18. Thus, the magnetic assembly 11 is locked against rotation on the hub body 14.

As seen in FIG. 1, the end plates 22 are provided with frusto conical counter bores 22a, the end portions 23a of the tie rods 23 are in the counter bores, and welds 27 permanently secure the magnetic assembly together.

In assembling the magnetic assembly 11 on the hub 14, one of the clamping collars 12 is screwed into place, the magnetic assembly 11 is slid onto the hub 14 and abutted against the collar 12, and the other collar 12 is then screwed into place to clamp the magnetic assembly between the collars. The bearers 13 are then heated and placed around the shaft areas 16 of reduced diameter where they are permitted to shrink into engagement with said areas as they cool.

Referring now to FIGS. 1 and 4, the magnetic assembly 11 includes register pins 28 which project a short distance from the surface of the magnetic assembly in order to be engaged by register holes in printing plates mounted on the cylinder. The magnetic assembly 11 is bored radially to provide holes 29, and threaded bushings 30 are driven into the holes 29. The register pins 28 have threaded shanks 28a which screw into the bushing 30, and a shoulder 30a in the bushing provides a seat for the head of the register pin 28.

The foregoing detailed description is given for clearness of understanding only and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

3 I claim: 1. A magnetic printing cylinder comprising, in combination: 7

a shaft having a hub of uniform diameterand end portions of reduced diameter; a magnetic assembly that makes a sliding fit on said hub, said magnetic assembly comprising alternate thin carrier ring means of non-magnetic material and thin annular pole pieces of magnetic material, said carrier ring means and said pole pieces having planar faces which abut over their entire facing areas, and each of said carrier ring means having a plurality of magnet mounting holes about its circumference,

a magnet in each of said holes, said magnets having their poles abutting the faces of the pole pieces and there being like poles abutting both faces of each pole piece so alternate pole pieces are of opposite polarity,

non-magnetic annular end plates at the ends of the assembly,

and a plurality of tie rods impaling both end plates, the carrier ring means and the pole pieces to form them into a unitary assembly which may be mounted on and removed from the hub as a unit;

interengaging means preventing rotation of the magnetic assembly on the hub;

threaded means at the ends of the hub between which the magnetic assembly is clamped;

and bearers retained on the reduced diameter end portions of the shaft by a shrink fit.

2. The combination of claim 1 in which each carrier annular plates means consists of a plurality of identical rings.

3.v The combination of claim 1 in which each carrier ring means is about twice as thick as each pole piece.

4. The combination of claim 1 in which the tie rods have their end portions in counterbores in the end plates, and meansjare provided bonding the end portions of the tie rods in the counterbores.

5. The combination of claim 1 in which the interengaging means comprises a keyway in the hub body, a key in the keyway, and aligned notches in the magnetic assembly engaged by the key.

6. The combination of claim 1 in which the annular pole-pieces have central openings of a diameter greater than that of the hub, so there is a gap between the hub and the pole pieces.

7. A magnetic printing cylinder comprising, in combination:'

a shaft having a hub of uniform diameter,

threaded areas at the ends of the hub, and areas of reduced diameter adjacent the threaded areas at the extremities of the shaft;

bearer rings secured to the areas of reduced diameter by a shrink fit;

threaded collars screwed onto said threaded areas, whereby the bearer rings may be heated to loosen them and may be pushed off the shaft. by rotating each collar in a direction to move it away from the hub;

a plurality of thin carrier ring means of non-magnetic material that make a sliding fit on said hub, each of said ring means having planar faces and having a plurality of uniformly circumferentially spaced magnet mounting holes;

a magnet in each of said holes, said magnets having their poles at the faces of the ring means;

a plurality of thin, annular magnetic pole pieces that have their inner edges spaced circumferentially from the hub,

said carrier ring means and said annular pole pieces being mounted on the hub with a pole piece between each two carrier ring means and like poles abutting both faces of each pole piece so alternate pole pieces are of opposite polarity;

interengaging means between the hub and the carrier ring means preventing rotation of the carrier ring means and the annular pole pieces on the hub;

and a plurality of tie rods impaling the carrier ring means and the pole pieces.

8. The combination of claim 7 which includes a plurality of register pins embedded in the carrier ring means and the pole pieces and extending radially therefrom.

9. The combination of claim 8 in which there are radially extending holes in the surface of the carrier ring means and pole pieces, there are internally threaded bushings press fitted into said holes, and the register pins consist of threaded studs which are screwed into the bushings and have their heads projecting radially.

10. A magnetic assembly adapted to slide onto a hub of a shaft to form a magnetic printing cylinder, said assembly comprising, in combination:

alternate thin carrier ring means of non-magnetic material and thin annular pole pieces of magnetic material, said carrier ring means and said pole pieces having planar faces which abut over their entire facing areas, and each of said carrier ring means having a plurality of magnet mounting holes about its circumference,

a magnet in each of said holes, said magnets having their poles abutting the faces of the pole pieces and there being like poles abutting both faces of each pole piece so alternate pole pieces are of opposite polarity,

non-magnetic annular end plates at the ends of the assembly,

and a plurality of tie rods impaling both end plates, the carrier ring means and the pole pieces to form them into a unitary assembly which may be mounted on and removed from the hub as a unit.

1 l. The magnetic assembly of claim 10 in which each carrier ring means consists of a plurality of identical rings.

12. The magnetic assembly of claim 10 in which each carrier ring means is about twice as thick as each pole piece.

13. The magnetic assembly of claim 8 in which the tie rods have their end portions in counterbores in the end plates, and means are provided bonding the end portions of the tie rods in the counterbores.

14. The magnetic assembly of claim 10 in which aligned notches in the end plates and carrier rings form a continuous keyway.

15. The magnetic assembly of claim 10 in which the annular pole pieces have central openings larger than those in the carrier ring means and the end plates, and said ring means and end plates make a sliding fit on the hub.

16. The magnetic assembly of claim 10 which includes a plurality of register pins embedded in the assembly and projecting radially therefrom.

17. The magnetic assembly of claim 16 in which there are radially extending holes in the surface of the assembly, there are internally threaded bushings press fitted into said holes, and the register pins consist of threaded studs which are screwed into the bushings and 

1. A magnetic printing cylinder comprising, in combination: a shaft having a hub of uniform diameter and end portions of reduced diameter; a magnetic assembly that makes a sliding fit on said hub, said magnetic assembly comprising alternate thin carrier ring means of non-magnetic material and thin annular pole pieces of magnetic material, said carrier ring means and said pole pieces having planar faces which abut over their entire facing areas, and each of said carrier ring means having a plurality of magnet mounting holes about its circumference, a magnet in each of said holes, said magnets having their poles abutting the faces of the pole pieces and there being like poles abutting both faces of each pole piece so alternate pole pieces are of opposite polarity, non-magnetic annular end plates at the ends of the assembly, and a plurality of tie rods impaling both end plates, the carrier ring means and the pole pieces to form them into a unitary assembly which may be mounted on and removed from the hub as a unit; interengaging means preventing rotation of the magnetic assembly on the hub; threaded means at the ends of the hub between which the magnetic assembly is clamped; and bearers retained on the reduced diameter end portions of the shaft by a shrink fit.
 2. The combination of claim 1 in which each carrier annular plates means consists of a plurality of identical rings.
 3. The combination of claim 1 in which each carrier ring means is about twice as thick as each pole piece.
 4. The combination of claim 1 in which the tie rods have their end portions in counterbores in the end plates, and means are provided bonding the end portions of the tie rods in the counterbores.
 5. The combination of claim 1 in which the interengaging means comprises a keyway in the hub body, a key in the keyway, and aligned notches in the magnetic assembly engaged by the key.
 6. The combination of claim 1 in which the annular pole pieces have central openings of a diameter greater than that of the hub, so there is a gap between the hub and the pole pieces.
 7. A magnetic printing cylinder comprising, in combination: a shaft having a hub of uniform diameter, threaded areas at the ends of the hub, and areas of reduced diameter adjacent the threaded areas at the extremities of the shaft; bearer rings secured to the areas of reduced diameter by a shrink fit; threaded collars screwed onto said threaded areas, whereby the bearer rings may be heated to loosen them and may be pushed off the shaft by rotating each collar in a direction to move it away from the hub; a plurality of thin carrier ring means of non-magnetic material that make a sliding fit on said hub, each of said ring means having planar faces and having a plurality of uniformly circumferentially spaced magnet mounting holes; a magnet in each of said holes, said magnets having their poles at the faces of the ring means; a plurality of thin, annular magnetic pole pieces that have their inner edges spaced circumferentially from the hub, said carrier ring means and said annular pole pieces being mounted on the hub with a pole piece between each two carrier ring means and like poles abutting both faces of each pole piece so alternate pole pieces are of opposite polarity; interengaging means between the hub and the carrier ring means preventing rotation of the carrier ring means and the annular pole pieces on the hub; and a plurality of tie rods impaling the carrier ring means and the pole pieces.
 8. The combination of claim 7 which includes a plurality of register pins embedded in the carrier ring means and the pole pieces and extending radially therefrom.
 9. The combination of claim 8 in which there are radially extending holes in the surface of the carrier ring means and pole pieces, there are internally threaded bushings press fitted into said holes, and the reGister pins consist of threaded studs which are screwed into the bushings and have their heads projecting radially.
 10. A magnetic assembly adapted to slide onto a hub of a shaft to form a magnetic printing cylinder, said assembly comprising, in combination: alternate thin carrier ring means of non-magnetic material and thin annular pole pieces of magnetic material, said carrier ring means and said pole pieces having planar faces which abut over their entire facing areas, and each of said carrier ring means having a plurality of magnet mounting holes about its circumference, a magnet in each of said holes, said magnets having their poles abutting the faces of the pole pieces and there being like poles abutting both faces of each pole piece so alternate pole pieces are of opposite polarity, non-magnetic annular end plates at the ends of the assembly, and a plurality of tie rods impaling both end plates, the carrier ring means and the pole pieces to form them into a unitary assembly which may be mounted on and removed from the hub as a unit.
 11. The magnetic assembly of claim 10 in which each carrier ring means consists of a plurality of identical rings.
 12. The magnetic assembly of claim 10 in which each carrier ring means is about twice as thick as each pole piece.
 13. The magnetic assembly of claim 8 in which the tie rods have their end portions in counterbores in the end plates, and means are provided bonding the end portions of the tie rods in the counterbores.
 14. The magnetic assembly of claim 10 in which aligned notches in the end plates and carrier rings form a continuous keyway.
 15. The magnetic assembly of claim 10 in which the annular pole pieces have central openings larger than those in the carrier ring means and the end plates, and said ring means and end plates make a sliding fit on the hub.
 16. The magnetic assembly of claim 10 which includes a plurality of register pins embedded in the assembly and projecting radially therefrom.
 17. The magnetic assembly of claim 16 in which there are radially extending holes in the surface of the assembly, there are internally threaded bushings press fitted into said holes, and the register pins consist of threaded studs which are screwed into the bushings and have their heads projecting from the surface of the assembly. 